Flow control apparatus



April 3, 1962 c. A. LEE

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3,628,298 FLUW CONTRGL APPARATUS Charles A. Lee, Newtown, Conn, assignorto Kimberly- Clark Corporation, Neenah, Wis, a corporation of DelawareContinuation of application Ser. No. 578,618, Apr. 17, 1956. Thisapplication Feb. 27, 1959, Ser. No. 796,098

16 Claims. (Cl. 162214) The present invention relates to the manufactureof felted web and sheet products from suspensions of fibrous materials,and has particular relation to the manufacture of paper on Fourdrinierpapermaking machines of the inlet or pressure-forming type.

This application is a continuation of my oopending application SerialNo. 578,618, filed April 17, 1956, for Flow Control Apparatus, nowabandoned.

In the ope-ration of inlet or pressure-forming type papermakingmachines, an aqueous suspension of fiber and such other papermakingmaterials as may be used, which suspension is commonly designated asstock, is supplied to a web-forming region through which theF-ourdrinier wire is moved. The stock reaches the wire as a relativelyhigh energy, flowing stream which is usually under substantial hydraulicpressure. Examples of these machines are shown in United States PatentsNos. 2,060,808; 2,134,408; 2,225,435, and 2,308,370.

Prior to the developments of the inlet or pressure-forming typepapermaking machine it was the general practice in the operation ofFourdrinie-r papermaking machines to form the matte of fibers of whichthe paper web is composed by applying to the upper surface of theFourdrinier wire, as by flowing or spouting thereon, a layer of stockwhich was then caused or permitted to drain through the wire. The stockso applied to the wire contained the required amount of fiber in anamount of water which was sufficient to produce the proper distributionof the fibers in the web, and sufiicient drainage of water was effectedduring the period of time that the formed web remained on the wire toproduce a coherent sheet, capable of being couched off at the downstreamend of the wire.

Various mechanisms, including suction boxes, table rolls, and waterdoctors were disposed beneath the wire for increasing the rate ofdrainage therethrough, and since there was no substantial pressuredifferential across the wire in the web-forming region along the Wire,the speed of operation of these machines was determined primarily by thecapacity and effectiveness of the drainage means.

in contrast with this arrangement, in the inlet or pressure-formingmachines, the stock, while contained within an enclosed flow conduit, isapplied to a restricted area section of the Fourdn'nier wire as the wireis moved across the discharge end of that conduit. During theweb-forming operation, the stock constitutes a confined, relatively highenergy, flowing stream, which is under substantial hydraulic pressure,i.e., the pressure energy component of the stream of stock applied tothe wire is usually quite large in relation to the velocity energycomponent. A large portion of the water in the stock mixure is therebyforced through the wire in the web-forming region at a relatively highrate, the flow through the Wire occurring primarily as a result of thesubstantial pressure ditferential existing across the forming wire inthe web-forming region. The usual pressure-forming machine is capable ofbeing operated at a much higher speed than the earlier type ofFourdrinier papermaking machines, and these machines have been quitewidely used in the paperrnaking industry, epescially in the manufactureof sheets having a basis weight up to about 15 to 20 pounds per standardteam of 500 sheets 24 x 36 inches.

However, such pressure-forming type machines possess certain inherentoperational limitations or deficiencies.

Patent When such machines are at speeds in excess of from about 1500 to2000 feet per minute, intermittent conditions of flow instability tendto occur. In addition to these operational difficulties, productdeficiencies also result as the operating speeds of pressure-formingmachines are increased.

In my prior applications, Serial Nos. 121,525 (now Patent No.2,756,651); 196,893 (now Patent No. 2,756,- 650); 242,519 (now PatentNo. 2,756,649); and 323,966 (now Patent No. 2,75 6,648), which werefiled on October 14, 1949; November 21, 1950; August 18, 1951, andDecember 4, 1952, respectively, certain of these conditions anddifliculties are discussed. Also, these prior applications disclosearrangements overcoming various of the flow instabilities previouslyreferred to, and set forth, in some detail, certain operationalprinciples applicable generally to pressure-forming and other machines.The applications further disclose and teach how these principles may beembodied in pressure-forming machines and other apparatus operable toaccomplish the manufacture of fibrous webs from fluid suspensions, topermit much higher speeds of operation and much better control of thecharacter and arrangement of the constituent fibers of the web than hasheretofore been possible.

The present invention is directed to the same general problem as myprior applications, i.e., the provision of improved apparatus andmethods for the manufacture of felted fibrous webs from fluidsuspensions of fibrous materials, and especially the provision ofimproved paperrnaking apparatus of the pressure-forming type.

The present invention also includes the discovery of additionalprocedures, methods, and apparatus, the use of which results in good webformation, i.e., very uniform fiber distribution in the web and alsoprovides for effective control of the machine direction to cross-machinedirection strength ratio in the web. Of particular importance in thisregard is the discovery that effective control of the machine directionto cross-machine direction strength ratio can be effected by control andadjustment of a flow control member which is located upstream of and invertically spaced relationship to the web-forming region and which iscapable of controlling the relative relation of the velocity andpressure energy components of the flowing stream of stock within theweb-forming region.

These and other features of the invention will be made more apparentfrom the following description and accompanying drawings as appliedparticularly to pressureforming or inlet type Fourdrinier papermakingmachines.-

In the drawings:

FIGURE 1 is a schematic view partially in vertical section and partiallyin side elevation of the Wet end of a Fourdrinier pressure-inlet typepapermaking machine embodying certain of the features of the inventionand certain accessory equipment;

FIGURE 2 is an enlarged vertical cross-sectional view of a portion ofthe machine illustrated in FIGURE 1, this view showing certain of thedetails and features of the Web-forming and flow control mechanisms inaccordance with the invention, which is embodied in that machine;

FIGURE 3 is an enlarged fragmentary sectional view of the web-formingsection of the machine illustrated in FIGURES 1 and 2;

FIGURE 4 is an enlarged fragmentary sectional View taken along the line44 of FIGURE 3; and

FIGURE 5 is a typical graph showing how the machine direction strengthto cross-machine direction strength ratio of a Web formed on apparatussuch as is illustrated in FIGURES 1 to 3 is related to the velocity ofthe forming roll and the velocity of the forming wire.

It will be appreciated that certain of the principles and arrangementsof the present invention are readily applicable to the older types ofexisting pressure-forming machines, and when so applied make possiblesubstantial improvement in the characteristics of the product beingmade, and substantial increase in the possible operating speeds of themachines, both under operating conditions which are substantially moreflexible and readily controlled than any arrangement heretoforedeveloped.

The diagrammatic view, FIGURE 1, illustrates the structure andarrangement of a pressure-forming or inlet type Fourdrinier papermakingmachine of the general character to which the present application hasparticular application. As there shown, the Fourdrinier wire 11 issupported upon a breast roll 13 and a couch roll 15 and is adapted topass over a plurailty of spaced table rolls 17 and suction boxes 1?. Thewire 11 is tensioned by additional guide or tensioning means asillustrated at 21. The wire 11 is driven by suitable drive means which,in the illustrated structure, includes a main drive and a helper drive.The main drive connects with the couch roll 15 and supplies a majorportion of the energy necessary for driving the wire 11. The main driveincludes a motor 18, sprockets 20, and a chain drive 22. The

helper drive connects with the breast roll 13 and supplies a portion ofthe energy for driving this roll. The helper drive includes a motor 23,sprockets 25, and a chain drive 27. The main drive and the helper driveare suitably interconnected or synchronized so that the periphery of thebreast roll 13 moves at the linear velocity of the wire 11.

A tray 29, which is adapted to collect the white water, i.e., the liquidwhich drains through the wire during the web-forming operation, isdisposed within the upper and lower reaches of the wire 11, asillustrated, and this tray is arranged to discharge into a mixing tank31, which is normally maintained about three-fourths filled. Fresh waterfor make-up purposes may be added to the mixing tank through the pipe33, and additional stock, as is necessary to maintain the properconsistency of fiber concentration in the fluid suspension or stockbeing delivered to the web-forming region, is added through a secondinlet pipe 35.

The bottom of the mixing tank 31 is inclined, as shown, and a main flowline 37 connects to the tank at the lower end thereof. The main flowline includes a branch extension 39 having a valve 41 therein for use indraining the mixing tank 31, and the main flow line also connects withthe inflow side of a stock or fan pump 43, which is the principal meansrelied upon to deliver stock to the web-forming region of the machine.

The outlet of the fan pump 43 is connected to the inlet structure of themachine by suitable piping, indicated generally at 45. Included in thispiping is an automati cally operable pressure-regulating valve 47, atransition section 49, which converts the circular cross-sectionalstream delivered by the fan pump and piping to a stream of rectangularoutline, and a flow spreader 51. The flow spreader 51 accomplishes thefunction of converting the uniformly dimensioned stream delivered by thetransition section 49 into a relatively shallow stream of rectangularcross section which desirably has a transverse width substantially equalto the cross-machine width of the Webforming region of the machine.

The outlet end of the flow spreader 51 is connected to the web-formingregion of the machine by a conduit 53 which is provided in the upstreamend of a flow control unit 55 which embodies various of the features ofthe present invention. The conduit 53 is rectangular in cross sectionand of the same dimensions as the outlet end of the flow spreader 51.The piping 45 also includes a by-pass line 57 which connects the outletside of the fan pump 43 upstream of the pressure-regulating valve 47,with the mixing tank 31, as shown. The by-pass line 57 includes ashut-01f valve 59. Suitable showers or sprays, indicated generally at61, are provided for effecting continuous cleaning of the rolls andwire, in accordance with usual papermaking practices.

The particular breast roll 13 constituting a part of the apparatusillustrated in FIGURES l and 2 is of the opensurfaced type and isillustrated in some detail in FIG- URES 2, 3, and 4. As there shown, thebreast roil 13 comprises a cylindrical inner shell 63 Which'may be ofbronze or other corrosion resistant material, and which is supported forrotation by means of a pair of shaft sections 65, each of which ismechanically connected to one end of the shell by a suitable annularheader 67. As shown in FIGURE 4, each of the headers 67 is welded orotherwise attached at its periphery to one end of the shell 63 and thehub of each of the annular headers is welded to the inner end portion ofone of the two shaft sections 65. The outer ends of the shaft sections65 extend into suitable supporting bearings (not shown). At least one ofthe shaft sections extends outwardly beyond its associated bearing andsupports a sprocket 25 which connects with the chain drive 27.

At spaced intervals along the shell 63, the roll 13 is provided with aplurality of outwardly-projecting ring units 69. The rings 69* areintegrally attached to the shell 63 and are provided with spaced,radially extending notches 71 (FIGURE 3) which support a plurality ofelongated bar or vane members 73. These vane members are inclined in thedirection of rotation of the roll 13, as shown particularly in FIGURE 3,and extend longitudinally of the roll surface with the longitudinal axesthereof substantially parallel to the axis of rotation of the roll.

The spaced vane members 73 are used to receive and to hold temporarilythe liquid Which is forced through the wire and the adjacent underlyingsurface of the roll 13 during the web-forming operation. Each of thevanes 73, as shown particularly in FIGURE 3, includes a base or rootportion which is rectangular in cross section, and which is adapted tofit within the radiallyextending vane-supporting notches 71 in the ringunits 69. The upper portion of each vane is disposed at an angle ofabout to the root portion of the vane.

The outer edge portion of each of the vane units 73 is also notched, asshown particularly at 75 in FIGURE 4, and during the manufacture of theroll 13, an edgewise disposed ribbon 77 of Monel or other corrosionresistant material is wound into these slots 75 so as to provide ahelical coil of closely spaced turns which extend along the periphery ofthe roll 13 This is shown particularly in FIGURE 4, and it will be notedthat the helical ribbon projects above the outer edges of the vanes.This arrangement permits free circulation of liquid between the cells orcavities formed in the roll periphery by the spaced vanes 73, and italso minimizes vane shadows in the formed web.

In roll constructions of the general type illustrated, the vanes 73 arepreferably spaced within the range of from about to inch along the rollperiphery, and the turns of the edgewise-wound wire ribbon 77 whichdefines the outer surface of the breast roll 13 should be spacedsufliciently close together to prevent appreciable deformation of theforming wire during the operation of the machine. In a practicalembodiment of the invention, where the breast roll 13 had an overalidiameter of approximately 36 inches, the helical ribbon winding waswound at a pitch of 10 turns to the inch, and constituted a strip ofmonel ribbon having a thickness of .023 inch, and a cross-sectionaldimension of .210 inch. In this same construction, the edges of thevanes 73 were about .0625 inch below the outer peripheral edge of theribbon 77. A coarse mesh woven wire covering, such as a 12-14 meshscreen (not shown), may be applied over the ribbon winding, if desired.

As shown in FIGURE 4, each end of the breast roll 13 includes a pair ofouter, interengaged protective end rings 79 and 81 which are held inposition by means of cap screws 83. Each of the outer end rings 81extends beyond the outer periphery of the cylindrical shell 63 toapproximately the outer peripheral edge of the ribbon 77, and includes alaterally extending flange portion 85 which overlies a portion of theouter peripheral surface of the adjacent annular header 67. Theinnermost ends of the flange portions 85 extend vertically downwardlyinto contact with the outer surface of the cylindrical shell 63 andengage notches in the end sections of the vanes 73, thereby locking thevanes in position. The particular arrangement of the vane elements 73and the ribbon support 77 for the forming wire present a minimum ofresistance to the flow of fluid through the wire into the breast roll.At the same time, the vanes 73 are operable to retain the liquid whichis received therein during the period in which the forming wire movesout of the web-forming region.

Referring to FIGURE 2, it will be seen that the flow control unit 55includes a lower or stationary section 87 and a pair of hingedlyinterconnected, generally horizontally aligned upper sections 89 and 91,the section 89 being supported directly on the stationary section 87.The lower section 87 includes suitable plate and structural elementswhich define a frame portion having a flat upper surface 98, a pair ofupwardly-extending sides 92, and the walls of the closed conduit 53through which the stock is conducted to other elements of the flowcontrol means.

The upper sections 89 and 91 of the flow control unit are likewise offabricated construction and each includes oppositely arranged side walls93 and 95, respectively, which are connected together by suitabletransversely extending structural members to define a pair of generallyhorizontally disposed box structures. The box-like sections 89 and 91are generally horizontally aligned with the section 91 located forwardlyof the section 89. The upper section 89 is supported upon the flat uppersurface 90 of the frame portion of the stationary section 87 in a mannerso as to be movable longitudinally of the apparatus, thus permitting thesections 89 and 91 to move towards and away from the vertical centerline of the breast roll 13.

To facilitate the accomplishing of this movement, the side walls 92 ofthe stationary section 87 are provided with guideways 97 adapted toreceive and coact with suitable guide members 99 constituting anintegral part of the side walls 93 of the adjustable upper section 89.The coacting guideways 97 and guide members 99 serve the additionalfunction of preventing the hydraulic pressure which is developed withinthe flow passageways of the flow control unit 55 from displacing theadjustable section 89 relative to the lower stationary section 87. Tofurther aid in accomplishing this, it is desirable that the guides andguideways shall be constructed to very close tolerances. It may also befound desirable to include seals such as for example the O-ring typeseal illustrated at 101 between the engaging surfaces of the upper andlower sections 87 and 89 to minimize the possibility of fluid leakage inthe operation of the system. Locking screws as illustrated at 103 may beused to aid in holding the sections in proper adjustment.

In order to adjust the horizontal position of the upper sections 89 and91 relative to the center line of the breast roll 13, suitable drivemeans such as a motor 105 which is supported on the upper surface 90 ofthe stationary section 87 is suitably connected through suitable gearmeans (not shown) to one or more longitudinally extending, threadedshafts 107 which engage internally threaded passageways 109 within arear, transversely extending structural member 111 of the section 89.The threaded shafts 107 are arranged for simultaneous rotation by thedrive means. In this manner, it is possible to move the adjustable uppersections 89 and 91 of the flow control unit 55 towards and away from thecenter line of the breast roll 13 and thereby vary the 6 dimensions andrelative location of the web-forming region on the wire 11. The plane ofseparation between the upper and lower sections 89 and 87, which planeis coincident with the surface 90, normally extends substantiallyparallel to the surface of the horizontal position of the forming wire11.

The flow conduit 55 through which the stock is conducted from thedischarge end of the flow spreader 51 is rectangular in cross sectionand may have the same crosssectional area and dimensions as that end ofthe flow spreader. In the structure illustrated in FIGURES 2 and 3, thelower surface of the flow conduit 53 extends in a horizontal directionadjacent and beyond the forward end of the rearward adjustable section89. This lower surface approaches in a horizontal direction the uppersection of the lower, rearward quadrant of a transversely extending,cylindrical flow control member 113 which forms a portion of the forwardadjustable section 91 and then curves smoothly to a downward arcuatepath which is spaced below and which extends approximately parallel theadjacent surface of the roll 113. The end of the lower surface of theconduit 53 in the region adjacent the webforming region is defined by adownwardly extending apron plate 115 which extends transversely the fullWidth of the machine. The lower surface of the outer or lip portion 117of the apron plate is cut away, as shown, and desirably this surface iscurved so as to provide with the adjacent surface of the wire 11 whichis supported on the breast roll 13, a passageway 119 which is ofincreasing cross-sectional area in the direction opposite to thedirection of movement of the wire 11. The apron plate 115 extends withinsuitable guide means 121 provided in the adjacent portion of thestationary section 87 and is fixedly positioned therein by means such asscrews 123. The apron plate is provided with a suitable slot 125 whichpermits adjustment of the outer tip of the apron plate 115 relative tothe forming wire 11. Normally, the apparatus is adjusted so that the tipof the apron plate 115 is spaced approximately 1% to 2 inches rearwardlyof the center line of the breast roll 13.

The lower adjacent ends of the sections 89 and 91 are pivotallyinterconnected through hinge members 127 and 129, respectively, whichextend outwardly from the lower edges of these sections. These pivotalhinge members 127 and 129 extend transversely the full width of themachine and have lower surfaces which form continuations of the lowerwalls of these sections, thus permitting stock to flow smoothly betweenthese lower surfaces. A suitable seal such as the O-ring type sealillustrated at 131 may be provided between the engaging surfaces of thehinge members to minimize the possibility of fluid leakage in theoperation of the apparatus.

The hinge members 127 and 129 are maintained in contact with each otherby biasing means which includes suitable nut and bolt assemblies 133which extend through enlarged openings 135 and 137 in the transversesupporting walls of the sections 89 and 91 adjacent the hinge members127 and 129 and springs 139 which extend around the outer ends of thebolts and bear against the inner faces of these transverse supportingwalls. The two upper sections 89 and 91 are also interconnected throughan upwardly and forwardly extending overhead arm which is connected atits lower end to the upper forward end of the section 89, anintermediate arm or link 132 which is pivotally connected at its upperend to the outer end of the overhead arm 130, and a member 134 which ispivotally connected at its upper end through an eccentric connection tothe arm 132 and which is connected at its lower end to the upper end ofthe section 91. The vertical position of the outer end of the section 91may be adjusted by rotating the shaft 136 of the eccentric connection.

The upper forward section 91 of the flow control unit 55 includestransversely extending structural elements 141 integrally attached tothe side walls which define the walls of a generally cylindrical flowcontrol chamber 143, and the cylindrical flow control member 113 whichis disposed within the flow control chamber in generally symmetricalrelation thereto. The unit also includes an adjustable member indicatedgenerally at 145 which is positioned at the inflow side of the flowcontrol chamber, and a slice 147. As may be seen in FIGURE 3, the slice147 is wedge-shaped with its apex or leading edge located upstreamadjacent the surface of the cylindrical flow control member 113. Theupper surface of the slice 147 extends upwardly along an arcuate pathand forms a portion of the wall of the cylindrical chamber 143 and thelower surface of the slice 147 extends downwardly in a directiongenerally parallel to the upper surface of the apron plate 115 andterminates adjacent the wire 11. The lower edge of the slice 147 definesthe downstream edge of the pressure-forming zone on the wire 11.

'In the particular apparatus illustrated in FIGURES 2 and 3, the flowcontrol member 113 comprises a closed cylinder or roll whose surface isprovided with transversely extending, saw-toothed roughness elements149, as shown, and is supported for rotation within the cylindricalchamber 143 by suitable supporting shaft sections 144 which extend intobearings, not shown. The peripheral diameter of the flow control membershould be almost as large as the diameter of the flow control chamber143. In general, the diameter of the flow control member 113 should bewithin /a inch, and preferably within between 7 and /8 inch of thediameter of the flow control chamber 143.

The flow control member 113 is connected to a drive means in order thatit may be driven at predetermined speeds during the operation of theapparatus. The roll drive means, which may include a motor 151,sprockets 153, and a drive chain 155, should be capable of driving theroll at relatively high speed. For example, in a structure using a flowcontrol roll approximately 16 inches in diameter, and having anoperational or wire speed of about 2000 feet per minute, the drive meansshould be capable of driving this roll at a speed within the range of100 to 800 r.p.m. during normal operating conditions of the machine.

The adjusting member 145 embodied in the illustrated apparatus is notnecessary for the purposes of the present invention and may be replacedby a fixed wall section which curves downwardly so as to direct theupper portion of the moving stream of stock from a horizontal directionto a direction approximately tangential to the surface of the flowcontrol roll 113. The adjustable mechanism 145 is provided in order topermit the mechine to be converted to other types of operation (notshown) where a throttling mechanism at the inflow end of the flowcontrol chamber is desirable. The adjustable mechanism 145 includes abar or vane member 157 which extends completely across the width of themachine and which is supported for limited movement towards and awayfrom the adjacent lower surface of the conduit 53 by means of suitableguide means 159 which are integrally attached to the transverselyextending structure of the flow control section 91.

Movement of the vane member 157 and accurate positioning of that memberis accomplished by means of a plurality of spaced rods 1.61, each ofwhich is connected at one end to the member 157 and provided with athreaded end portion 163 at its other end. The threaded end portions 163engage suitable internally threaded gear wheels 165 which are supportedon the frame of the upper section 91 of the flow control unit. Thesegear units are rotated in unison by coacting worm units 167 supportedupon and keyed to a suitable actuating shaft 169. This arrangementpermits the member 157 to be moved so as to vary and adjust the verticalheight of the lower end of that member. The lower surface of the member157 and the guide means 159 are suitably cut away, as shown, to directthe flowing stream tangentially into the flow control chamber 143 and toconform generally to the outline of the stream lines existing in theflow pattern within the apparatus during operation.

To prevent leakage along the sides of the vane member 157, it isdesirable to include sealing means, such as the resilient O-ring seals171 located intermediate the member 157 on the sides of the guidesupport 159 therefor.

It is desirable that the breast roll 13 be supported in such manner thatits position relative to the flow control unit 55 can be accuratelyadjusted; this in conjunction with the adjustable apron plate 115 andthe permissive fore and aft adjustment of the upper sections 89 and 91of the flow control unit making possible very close control andadjustment of the dimensions of the webforming region and the flowpassageways adjacent that region. Adjustment of the position of thebreast roll 13 is most easily accomplished by the use of anautomatically operable adjustable roll support of an hydraulic or othertype. Such mechanisms are commercially available and will not bedescribed in detail.

The wedge-shaped slice or discharge lip structure 147 forms an importantpart of the present apparatus. In the disclosed structure, the slice 147is formed of two mating sections 173 and 175, the upstream ends of whichabut against a member 177 which is affixed to the transverse structureof the section 91 by means of screws 179 or the like. The slicestructure 147 which includes both slice sections 173 and 175 is fixedlysecured to the member 177 by means of tongue and groove connections 181and 183 and bolts 185 which extend through the member 177 and arethreadably received in the slice section 173.

The leading edge of the slice 147 is located upstream of the center lineof the cylindrical roll 113. It should also be as close as possible tothe surface of the roll 113 and preferably should be spacedapproximately 4 inch therefrom. The wedge-shaped slice structure 147presents a narrow leading edge to the flowing stream which directs theupper portion of the moving stream of stock in the direction of theforming region, i.e., it tends to peel the high velocity fluid which ismoving in an arcuate path around the surface of the roll 113 and todirect this fluid downwardly toward the forming region. The slicesection 175 has a lower surface which is inclined at a somewhat steeperangle than the lower surface of the slice section 173. This increasedslope provides additional clearance between the wire and under-surfaceof the slice immediately upstream of the outer edge of the slice. Themember 175 is removable in order to provide easy replacement thereof dueto the wearing away of its lower edge during use. The downstream surfaceof the slice structure 147 provides with the adjacent surface of thewire 11 a flow passageway of substantial length and constantlydecreasing in cross-sectional area in the direction of movement of thewire 11, and the formed web. This arrangement in combination with theavailable adjustment of the downstream edge or lip of the slice plate115 makes possible accurate control of the amount of stock which isdischarged from the flow control unit 55 on top of the formed web and isof important value in assuring satisfactory operation of the mechanism.

The two sides of the flow control chamber 143 are enclosed by the endwalls of the flow control section 91 and suitable sealing units 187which are adapted to ride on the wire 11 during machine operation. Thesesealing units 137 may be similar to the sealing unit shown in FIGURE 4,comprising L-shaped sections 189 of rubber or other resilient materialwhich is backed by a rigid metal angle 191, the entire structure beingadjustably held in position by a support 193, which is bolted to theside of the flow control unit by suitable bolts 195.

In the operation of apparatus of the type illustrated in FIGURES 1through 3, the stock is delivered to the inlet to the flow controlchamber 143 as a high energy flowing stream having substantial velocityand pressure energy components. This is accomplished by delivering thestock from the fan pump 43 at a relatively high head and by throttlingthe stock adjacent the inlet to the flow control chamber 143. Aspreviously pointed out, the stock which is delivered to the wire 11downwardly in a generally curved path around the lower upstream quadrantof the cylindrical roll 11?: to the leading edge of the outlet slice 173and thence in a path which is generally tangential to the roll surfaceand extending to the wire 11. Since the leading edge of the slice isupstream of the center line of the roll 113, the axis of the stream ofstock is oblique to the plane of the wire 11 in the webforming region.

Within the flow control chamber 143, the stream of stock which isgenerally rectangular in cross-sectional outline, flows into contactwith the outer periphery of a second stream of stock which is flowing ina generally vorticular path around the rotating cylindrical roll 113.The velocity of this vorticularly flowing stream is generallyconsiderably greater than the velocity of the stock entering the flowcontrol chamber 143. Since the pressure within the vorticular stream isconsiderably less than the pressure of the stream entering the formingchamber 143, the upper layers of the stream of stock entering the flowcontrol chamber adjacent the surface of the dew control roll 113 arecaused to increase in velocity to a somewhat greater extent than thelower layers of the stream of stock which are spaced from the rollsurface. As the stream of stock moves within the flow control chamber143 below the lower upstream quadrant of the rotating roll 113, there isa partial intermixing of the vorticular stream with the stream which isdelivered from the fan pump 43, causing an increase in the averagevelocity of the stream moving towards the forming wire 11. Thisintermixing action is accompanied by a conversion of the velocity energycomponent of a portion of the stream into pressure energy, together withthe creation of a fine-scale turbulence condition. At a point upstreamof the vertical center line of the rotating roll, the stream comes intocontact with the leading edge of the wedge-shaped slice 147. The leadingedge of the slice 147 closely approaches the surface of the rotatingroll 113 so as to peel off as large an amount of the faster moving upperportion of the stream as possible and to direct the stream towards theforming wire 11. As the higher velocity stream portion flows adjacentthe lower surface of the slice member, it slows down due to its contactwith both the stationary slice wall and the underlying, slower movingportion of the stream. The slowing down of this faster moving fluidhelps to maintain the velocity of the underlying fluid so that thehorizontal component of the velocity of the fluid passing through theforming wire does not appreciably vary throughout the web-formingregion.

The high velocity vorticular flow which is used to effect an increase ofvelocity of the fluid moving towards the web-forming region as well asto maintain the horizontal component of the velocity of the fluidpassing through the forming wire approximately constant is produced bythe recirculation of a quantity of the stock around the rotating roll113 within the flow control chamber 143. The velocity of therecirculating vorticular stream is controlled and determined by thespeed of rotation of the cylindrical roll 113 within the flow controlchamber 143.

It will be appreciated that means other than the throttling of the fluidcan be employed in the production of the high energy stream entering theflow control chamber 143, for example, a flow channel of suitabledimensions might be employed, although this arrangement has thedisadvantage of introducing rather serious head and energy losses withinthe flowing stream, especially if the channel should be of substantiallength.

One of the important discoveries constituting part of the presentinvention is the discovery that the flow instabilities which arenormally incident to the rotation of a smooth cylindrical roll within anenclosed cylindrical chamber may be effectively controlled by reducingthe spacing between the roll surface and the outer chamber to a value ofless than 7 inch and adding roughness elements to the outer surface ofthe roll which increases the friction between the roll surface and theflowing stream. The actual roughness pattern may be varied considerably.The important considerations in this regard are the height of theroughness elements and the spacing index of the roughness, that is, theratio of the spacing between the roughened elements circumferentiallyaround the roll to the depth of the roughness elements on the surface ofthe roll. The height of the roughness elements should be between andinch and the spacing index should be between 4 and 12 and preferablyabout 8 for maximum eifectiveness in controlling flow disturbances inthe flowing stream between the roll surface and the wall of the flowcontrol chamber.

Another of the important discoveries constituting a part of the presentinvention is the discovery that the ratio of the machine directionstrength to the cross-machine direction strength of the formed web canbe varied by adjustment and control of either the speed of the flowcontrol roll 113 or the speed of the forming wire 11 during theoperation of the apparatus.

More particularly, it has been discovered that with the use of apparatusof the type illustrated in FIGURES 1 through 3, the ratio of the machinedirection strength to the cross-machine direction strength in the formedweb is related to the linear velocity of the forming roll 113 and to thevelocity of the forming wire 11 by the following generalized empiricalequation:

MD V, CD w where: M is a constant which is related to the geometry ofthe slice: k is a constant which is related to the carding action of thewire; V is the tangential velocity of the forming roll; and V is thetangential velocity of the wire. A typical graph of machine directionstrength to crossmachine direction strength ratio versus for apparatusof the type described is shown in FIG- URE 5.

In one typical installation used in the manufacture of tissue having abasis weight of up to 8 or 9 pounds per standard ream from a furnishconsisting of 25 percent bleached sulphite and 75 percent bleachedsulphate with a consistency of about .20 percent, the wire 11 was set torun at a constant speed of 2,500 feet per minute and the fan pump 43delivered approximately 12,000 gallons of stock per minute at a head ofapproximately 120 inches of water measured at the inlet of the flowcontrol unit. The vertical height of the approach conduit to the inletof the flow control chamber 143 was 3 inches and the vertical height ofthe flow passageway to the forming wire 11 within the flow control unitwas inch. The rotating cylindrical roll 113 was 18 inches in diameterand the spacing, between the cylindrical roll 113 and the wall of theflow control chamber 143 was approximately A; inch except at the leadingedge of the slice 147 where the spacing was about inch. The leading edgeof the slice 147 was located approximately 3 inches behind the centerline of the breast roll 13 and approximately inch behind the center lineof the cylindrical roll 113, and the tip of the outer lip portion 117 ofthe apron plate was located 1 /2 inches behind the center line of thebreast roll 13. The slice tip was set .015 inch from the surface of thewire 11, which distance was just sufficient to lubricate the web as itpassed beneath the slice tip. By adjusting the tangential velocity ofthe roll 113 in this installation within the range of 500 to 3,800 feetper minute, one could control the machine direction to cross-machinedirection strength 11 ratio of the formed web Within the range of 1 toabout 4.5.

When the horizontal velocity component of the stream passing through thewire 11 is less than the velocity of the forming wire, it is necessaryto accelerate the fluid which enters the breast roll. This isaccomplished in the disclosed apparatus by providing the breast roll 13with a helper drive which may supply as much as 75 percent of the forcenecessary to turn the breast roll, the wire 11 providing the remaining25 percent. Sufficient force must be supplied by the main drive to pullthe wire 11 under the slice 147 and across the various table rolls 17and suction boxes 19. It is, of course, necessary to interconnect orsynchronize the main wire drive and the helper drive so that theperiphery of the breast roll 13 moves at the linear velocity of theforming member 11.

With an approach conduit 3 inches in depth, it has been found that thedimension A, the depth of the stream passing through the flow controlchamber 143 towards the web-forming region, may vary from inch to 2 /2inches, openings of from inch to 1% inches being found especiallyuseful.

In general, the upstream edge of the slice 147 may be located from about2 /2 to 3 inches behind the center line of the breast roll 113 and thetip of the outer lip 117 of the apron plate 115 may be located fromabout 1% to 2 inches behind the center line of the breast roll Undermost operating conditions, it has been found that the pressuredififerential across the wire 11 in the web-forming region should be ata minimum in the upstream portion of the web-forming region and shouldincrease in the direction of movement of the forming wire. Thiscondition is achieved in the present apparatus by virtue of the slowingdown of the faster moving upper layer of the stream flowing above theforming wire due to frictional contact with the surface of the slice 147and with the underlying slower moving fluid and by the shape of theslice which because of the drainage of stock through the forming wirecoacts with the wire 11 to form a conduit section wherein the stream isdecelerated with accompanying increasing pressure.

As previously indicated, the upper boundary layer portion of the fluidwhich passes through the lower part of the flow control chamber 143 isrecirculated within the flow control chamber and therefore does notreach the web forming region. In this connection, as much as 30 percentof the flow may be recirculated around the dome. In addition, apredetermined part of the lower portion of the stream moving towards theweb-forming region will, under most conditions, be conducted out of theflow control chamber backwardly along the wire. When so operated, thearrangement results in the delivery to the web-forming region of onlythe central portion of the flowing stream which passes through the lowerportion of the forming chamber upstream of the slice.

In eifect, the main stream of stock passing into the flow control unit,which stream, as previously stated, is of generally rectangularcross-sectional outline, is joined by the vorticularly rotating fluidpassing around the dome which forms the upper part of the flow controlchamber 143, and the resultant stream may be considered as constitutingat least three divisions or layers. Each division constitutes a portionof the stream having the same width transversely of the stream as themain stream, and the three divisions are thus disposed layerwise inside-by-side relationship in the direction of movement of the formingmember. The central division passes directly through the fiow controlunit, first downwardly around the lower upstream quadrant of the formingroll 113 and then through the passageway formed by the apron plate 115and slice 147 into contact with the wire 11 or other web-forming member.The lower division is caused to flow backwardly along the wire 11 orother forming member as that member moves into the webforming region andthe third or upper division flows between the upstream tip of the slicemember 147 and the flow control roll 113 and is caused to berecirculated around the dome which forms the upper portion of theforming chamber.

It will be evident that this mode of operation results in the continuouscarrying away of the upper and lower boundary or surface layers of thestream of stock passing through the lower portion of the forming chamber14-3. In other words, the upper boundary layer which is in frictionalcontact with the forming roll 113 and the lower boundary layer which isin frictional contact with the apron plate 115, which layers areaffected by the frictional contact with those surfaces, are continuouslyremoved from the web-forming region with resultant important improvementin the hydraulic characteristics of the stream division which passesthrough the forming member.

In the control and adjustment of the operating conditions of papermakingmachines of the general type illustrated in FIGURES 1 through 3, themost important operating controls are the pressure at which the stock isdelivered to the inlet side of the flow control unit, the speed of theforming wire, the speed of rotation of the forming roll and the lengthof the web-forming region.

Under normal conditions of operation, the member is adjusted so as todirect the upper portion of the stream of fluid into the flow controlchamber 143 in a direction approximately tangentially of the roll 113.It therefore acts merely as a transition section for smoothing the flowof stock into the forming chamber 143. As previously indicated, for thepurposes of the present invention, one could substitute a stationarymember of proper shape and dimensions for the member 145. This has notbeen done in the illustrated embodiment to permit the conversion of thisapparatus to other types of operation (not shown).

Control of the velocity of the recirculating vorticular flow isaccomplished by the control of the speed of rotation of the flow controlmember 113. Since the velocity of the vorticularly moving fluid affectsthe velocity of the stream section which enters the web-forming region,a change in speed of rotation of the roll 113 will produce a change inthe horizontal velocity component of that portion of the stream whichpasses through the forming member. The speed of rotation of the roll 113will also aflect, to a certain extent, the pressure in the stream ofstock immediately above the forming member; however, a change in theroll speed will alter the magnitude but not the basic character of theincreasing pressure pattern within the stream of stock above the formingmember in the direction of movement of the forming member.

The physical dimensions of the forming region, specifically its lengthin the direction of wire movement, can be adjusted by changing thelongitudinal position of the upper section 91 of the flow control unitand to a slight extent by adjustment of the position of the apron plate115.

In accomplishing most satsifactory web formation and overall stabilityof operation under certain operating conditions, and especially duringvery high speed operation, it is desirable, as above noted, that aportion of the flowing stream of stock delivered to the web-formingregion flow backwardly along the moving wire 11 through the passagewayexisting between the under-surface of the apron plate lip 117 and theforming wire 11. When the stock velocity within the flow control unit ishigh, i.e., 1,500 to 2,000 feet per minute or higher, the instabilityconditions which are inherent in pressure-forming type machines tend toappear, and these instabilities can be avoided by the creation of astable, backwardly flowing stream of stock at the upstream end of theweb-forming region. This backwardly flowing stream stabilizes the flowat the upstream portion of the Web-forming region and effects thecreation of a line of stagnation points transversely across the machinein the region above and rearward of the apron lip 117.

When operating under conditions which involve relatively low wire speedsand low stock velocities, this tendency to instability is substantaillyreduced and under such conditions, it may not be necessary to providethe backwardly flowing stream of stock. The provision of the backwardlyflowing stream of stock at the upstream end of the web-forming regionhas, however, an important advantage over and above instability controlin that its removes from the web-forming region the lower boundary layerof the stream which is flowing through the flow control chamber towardsthe web-forming region. Since there is some slowing down of the lowerstream layers as they move along the lower wall of the flow controlchamber, the removal of that layer accomplishes the very desirableresult of assuring that only the central and upper portion of theflowing stream flows into the web-forming region. This materiallyfacilitates the adjustment of the flow velocity in the web-formingregion.

In most flow control units of the type described, it will rarely befound necessary to institute back-flow in excess of about 10 percent ofthe total flow into the flow control unit, and generally, back-flow inthe amount of 2 to 5 percent will usually be adequate.

The amount of stock which is recirculated within the flow controlchamber 143 will vary depending upon the relative dimensions of thecylindrical roll 113, and the flow control chamber 143, and the speed ofrotation of the roll 1113. In the manufacture of tissue web sheets atwire speeds within the range of 500 to 3,000 feet per minute by the useof machines of the type illustrated in FIGURES 1 through 3, and withstock having a consistency within the range of .08 to .25 percent, theamount of recirculating fluid will generally be within the range of from20 to 40 percent of the fluid approaching the slice member 147.

The amount of stock which flows out of the flow control unit 5'5 on topof the formed web is controlled by the positioning of the slice lip orother means defining the downstream edge of the pressure-forming region.Under all conditions of operation, it is advisable to so position theslice lip that there will be a suflicient amount of water on the wire asit passes beneath the slice lip to efiect lubrication of the web andprevent its derangement. Generally, a discharge with the formed web ofan amount of Water equal to from about 5 to 8 percent of the totalamount delivered to the flow control unit to effect formation of the webwill accomplish satisfactory lubrication of the formed web.

As indicated above, the slice mechanism 147 accomplishes the importantfunction of conducting the formed web out of the web-forming regionwithout disturbing or deranging the web fibers. This involves theaccomplishment of a transition action during which the pressure existingin the formed web must be reduced from the pressure existing in theweb-forming region within the flow control unit to atmospheric pressure.

For the purposes of this application, the web-forming region may bedefined as that region wherein the concentration and deposition of thosefibers which ultimately constitute the formed web is actually takingplace. Alternatively, the web-forming region may be defined as thatregion wherein there is substantial flow through the web-forming memberof the white water or other fluid carrier for the fibers. In thedescribed apparatus where the amount of water discharged beneath theslice lip is merely suficient to lubricate the web, almost all of thefiber deposition and flow of white water through the Wire will occur inthe region included within radial lines drawn from the center of thebreast roll to the downstream edge of the apron plate lip and to theslice lip, which region might also be described as the region ofpressure at the start-up.

forming. There may be some deposition of fibers on the wire from thebackwardly flowing stream of stock which is discharged through thepassageway 119, although this is usually of a very small magnitude.

When papermaking apparatus of the type illustrated in FIGURES 1 through3 is to be placed into operation, the speed of the Wire 11, the fore andaft positioning of the upper section M of the flow control unit 55, thepressure at which stock is delivered to the flow control unit 55, thepositioning of the apron plate 11$, the vertical position of the slicestructure 147, and the speed of rotation of the cylindrical roll 113 areusually based upon approximate calculations. If an adjustable throttlingmember such as the member is used, one would initially adjust thatmember so that it directs the upper section or layer of the flowingstream into the flow control chamber in a direction generally tangentialto the surface of the cylindrical roll 113. The major adjustment andusually the initial adjustment aside from the member 145 will probablybe that of the speed of rotation of the cylindrical roll 113. Thisadjustment may conveniently be based upon examination of the sheet beingmanufactured. Adjustment of the vertical position of the slice 147 ismade to assure that the formed web is passing out of the web-formingregion without derangement. Some fore and aft adjustment of the flowcontrol unit 55 and even some minor adjustment of the relative positionof the breast roll 13 may also be found desirable, particularlyInspection of the formed web may be relied upon to a considerable degreefor determining the optimum position of the various control elements.

In the foregoing, I have disclosed a new form of pressure-formingapparatus and various principles of operation which are determinative ofthe relationship between machine direction and cross-machine directionstrength in webs which are manufactured on such appara tus. The use ofthese principles to attain any desired relationship between the machinedirection and crossmachine direction strength ratio and in theattainment of other formation properties have been set forth at somelength.

In addition, I have disclosed novel means for accomplishing the desiredvelocity and pressure control within the web-forming region, and alsoways in which this control can be used to change or affect the physicalproperties of the formed sheet.

The structural arrangements disclosed are applicable for use inconnection with existing equipment with only relatively minormodifications of that equipment. Moreover, important benefits can beaccomplished by the use of only part of the arrangements and proceduresdisclosed.

Certain of the features of the invention believed to be new are setforth in the appended claims.

What is claimed is:

1. In the manufacture of continuous fibrous webs under pressure-formingconditions by the use of a confined flowing stream of a fluid suspensionof fibrous material which is caused to How obliquely into contact with amoving, fluid-permeable forming member in a web-formin g region, theimprovement which consists in controlling the pressure and velocitydistribution within the flowing stream adjacent the forming member bydirecting the upper portion of the flowing stream at a point upstream ofthe webforrning region into a vortex wherein the fluid has a greatervelocity than the average velocity of the fluid within said flowingstream, causing a portion of said vorticularly moving fluid totangentially engage and partially interrnix with the upper layers ofsaid flowing stream, and maintaining said vortex by the controlledaddition thereof of substantial amounts of energy, said energy additionbeing effected by a driving means which is'located at the center of thevortex.

2. In the manufacture of continuous fibrous webs under pressure-formingconditions by the use of a confined flowing stream of a fluid suspensionof fibrous material which is caused to flow obliquely into contact witha moving, fluid-permeable forming member in a web-forming region, theimprovement which consists in selectively increasing the velocity withinvarious layers of said flowing stream upstream of said web-formingregion by directing the upper portion of the flowing stream upstream ofsaid webforming region into a vortex wherein the fluid has apredetermined velocity greater than the average velocity of said flowingstream, and causing a portion of said vorticularly moving fluid totangentially engage and partially intermix with the upper layers of saidflowing stream, maintaining said vortex by the controlled additionthereto of substantial amounts of energy, said energy addition beingeffected by a driving means which is located at the center of thevortex, and directing said flowing stream from the region of said vortexobliquely into the webforming region through a suitable conduit toeffect a predetermined pressure and velocity distribution within theflowing stream adjacent the forming member.

3. In the manufacture of continuous fibrous webs under pressure-formingconditions by the use of a confined flowing stream of a fluid suspensionof fibrous material which is of generally rectangular cross-sectionaloutline having a web-forming portion and at least one other portionwln'ch constitutes an upper boundary layer of said flowing stream, saidweb-forming portion being caused to flow into contact with a moving,fluid-permeable forming member in a web-forming region in such mannerthat the longitudinal component of the velocity of the webformingportion extends in a direction generally parallel to the direction ofmovement of said forming member as said forming member passes throughthe web-forming region, the improvement which comprises selectivelycontrolling the velocity of the various layers of said flowing streamupstream of the web-forming region by the addition of fluid of velocitygreater than the average velocity of said flowing stream into the upperlayers of said stream, conducting away the upper boundary layer of saidflowing stream upstream of said web-forming region and then directingthe web-forming portions of said flowing stream obliquely to theweb-forming region through a suitable conduit to effect a predeterminedpressure and velocity distribution within the flowing stream adjacentthe forming member.

4. In the manufacture of continuous fibrous webs under pressure-formingconditions by the use of a combined flowing stream of a fluid suspensionof fibrous material Which is of generally rectangular cross-sectionaloutline having a web-forming portion and at least two other portionswhich constitute upper and lower boundary layers of said flowing stream,said web-forming portion being caused to flow obliquely into contactwith a moving, fluidpermeable forming member in a Web-forming region insuch manner that the longitudinal component of the velocity of theweb-forming portion extends in a direction generally parallel to thedirection of movement of said forming member as said forming memberpasses through the web-forming region, the improvement which comprisesselectively controlling the velocity of the various layers of saidflowing stream upstream of the webforming region by adding fluid ofpredetermined velocity greater than the average velocity of said flowingstream into the upper layers of said stream, conducting away the upperboundary layer of said flowing stream downstream of said fluid additionand upstream of said forming region, and then directing the web-formingportion and lower boundary layer of said flowing stream to theweb-forming region through a suitable conduit to effect a predeterminedpressure and velocity distribution within the flowing stream adjacentthe forming member, and conducting away the lower boundary layer of saidflowing stream at the upstream end of the web-forming region and causingsaid lower boundary layer to flow backwardly along said forming member.

5. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, means for supporting said member and for moving saidmember through the web-forming region of said apparatus, a source ofsupply of a fluid suspension of fibrous material, a flow control unithaving an inflow opening connected to said source of supply and havingan outflow opening through which a flowing stream of said fluid isdischarged onto said forming member under pressure-forming conditions asthat member is moved through said web-forming region, said web-formingregion being located at the outflow opening of said flow control unit,said flow control unit including a generally cylindrical chamber throughwhich the fluid delivered to said web-forming region is caused to flow,a cylindrical rotor located within said chamber and means for rotatingsaid rotor within said chamber, the spacing between the rotor surfaceand the inner wall of said cylindrical chamber being less than inch overa major portion of the surface area of said rotor and the surface ofsaid rotor having roughness elements thereon whereby the flowinstabilities which are normally incident to the rotation of acylindrical roll within an enclosed cylindrical chamber are effectivelycontrolled.

6. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, means for supporting said member and for moving saidmember through the web-forming region of said apparatus, a source ofsupply of a fluid suspension of fibrous material, a flow control unithaving an inflow opening connected to said source of supply and havingan outflow opening through which a flowing stream of said fluid isdischarged onto said forming member under pressure-forming conditions asthat member is moved through said web-forming region, said web-formingregion being located at the outflow opening of said flow control unit,said flow control unit including a generally cylindrical chamber throughwhich the fluid delivered to said web-forming region is caused to flow,a cylindrical rotor located within said chamber and means for rotatingsaid rotor within said chamber, the spacing between the rotor surfaceand the inner wall of the cylindrical chamber being less than A inchover a major portion of the surface area of said rotor, the surface ofsaid rotor including a plurality of spaced roughness elements, saidroughness elements being between and inch in height, and the ratio ofthe spacing between the roughness elements circumferentially around theroll to the depth of the roughness elements being between 4 and 12whereby the flow instabilities which are normally incident to therotation of a cylindrical roll within an enclosed cylindrical chamberare effectively controlled.

7. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, a breast roll for supporting said member formovement into and "through the web-forming region of said apparatus, asource of supply of a fluid suspension of a fibrous material, and a flowcontrol unit having an inflow opening connected to said source of supplyand having an outflow opening through which a confined flowing stream ofsaid fluid is discharged onto said forming member under pressure-formingconditions as that member is moved through said web-forming region, saidweb-forming region being located at the outflow opening of said flowcontrol unit, said flow control unit including an upper and a lowersection, portions of which define the walls of a generally cylindricalflow control chamber which is closed except for a pair ofcircumferentially spaced openings through which the fluid delivered tosaid web-forming region is caused to flow, a transversely extending flowcontrol member forming a portion of said upper section disposed withinsaid chamber so as to provide a re-entrant passageway within saidchamber within which the uppermost surface layer of the flowing streamof fluid is continuously circulated during operation of said apparatus,the upper section of said flow control unit being pivotally connected atits lower upstream end within said appara- 17 ins and adjustable meansfor rotating said upper section about said pivotal connection, therebypermitting an adjustment of the position of said flow control unitrelative to said forming member.

8. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, a breast roll for supporting said member formovement into and through the web-forming region of said apparatus, asource of supply of a fluid suspension of a fibrous material, and a flowcontrol unit having an inflow opening connected to said source of supplyand having an outflow opening through which a confined flowing stream ofsaid fluid is discharged onto said forming member under pressureformingconditions as that member is moved through said web-forming region, saidweb-forming region being located at the outflow opening of said flowcontrol unit, said flow control unit including an upper and a lowersection, portions of which define the walls of a generally cylindricalflow control chamber with the major axis thereof extending transverselyto the direction of movement of the webforming member and a forwardlyextending, downwardly directed conduit, said cylindrical chamber beingclosed except for a pair of axially extending, circumferentially spacedopenings through which the fluid delivered to said web-forming region iscaused to flow, one of said openings forming said inflow opening andtheother of said openings forming an inlet opening into said conduit, theother end of said conduit forming said outflow opening, a transverselyextending, cylindrical rotor forming a portion of said upper sectiondisposed within said chamber so as to provide a re-entrant passagewaywithin said chamber, within which the uppermost surface layer of theflowing stream of fluid is continuously circulated during operation ofsaid apparatus, the circulatory flow of fluid through said chamberintermixing with the main stream of fluid upstream of said web-formingregion to thereby establish a predetermined velocity of the flowingstream in the webforming region in the direction of movement of theforming member in response to the rotation of said rotor, adjustabledrive means for controlling the rotation of said rotor, the uppersection of said flow control unit being pivotally connected at its lowerupstream end within said apparatus and adjustable means for varying theposition of said upper section about said pivotal axis, therebypermitting an adjustment ofthe position of said flow control unitrelative to said forming member.

9. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, a breast roll for supporting said member formovement into and through the web-forming region of said apparatus, asource of supply of a fluid suspension of a fibrous material, and a flowcontrol unit having an inflow openingconnected to said source of supplyand having an outflow opening through which a confined flowing stream ofsaid fluid is discharged onto said forming member under pressureformingconditions as that member is moved through said web-forming region, saidweb-forming region being located at the outflow opening of said flowcontrol unit, said flow control unit including means defining the wallsof a generally cylindrical flow control chamber with the major axisthereof extending transversely to the direction of movement of theforming member and a forwardly extending, downwardly directed conduit,said cylindrical chamber being closed except for a pair of axiallyextending, circumferentially spaced openings through which the fluiddelivered to said web-forming region is caused to flow, one of saidopenings forming said inflow opening and the other of said openingsforming an inlet opening into said conduit, the other end of saidconduit forming said outflow opening, a transversely extending,cylindrical rotor disposed within said chamber so as to provide are-entrant passageway within said chamber within which the uppermostsurface layer of the flowing stream of fluid is continuously circulatedduring operation of said apparatus, the circulatory flow of fluidthrough said chamher intermixing with the main stream of fluid upstreamof said web-forming region to thereby establish a predetermined velocityof the flowing stream in the web-forming region in the direction ofmovement of the forming member in response to the rotation of saidrotor, adjustable drive means for controlling the rotation of saidrotor, said cylindrical rotor being of a diameter such that the spacingbetween the rotor surface and the inner wall of the chamber is less thanA inch over a major portion of the surface area of said rotor, thesurface of said rotor including a plurality of roughness elements, saidspacing and roughness elements eflectively controlling the flowinstabilities which are normally incident to the rotation of a rotorwithin a cylindrical chamber, the upper wall of said conduit forming aslice member, the upstream edge of said slice member being spacedapproximately inch from the surface of said rotor so as to peel off aslarge an amount of fluid from adjacent the rotor as possible and todirect said fluid towards the forming member, and the forward edge ofsaid slice being positioned adjacent the forming member and defining thedownstream edge of the web-forming region, said upstream edge of saidslice member being located between about 2 /2 to 3 inches behind thecenter line of the breast roll and the lip of said apron plate beinglocated from about 1 /2 to 2 inches behind the center line of the breastroll.

10. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, a breast roll for supporting said member formovement into and through the web-forming region of said apparatus, asource of supply of a [fluid suspension of a fibrous material, and aflow control unit having an inflow opening connected to said source ofsupply and having an outflow opening through which a confined flowingstream of said fluid is discharged onto said forming member underpressureformi-ng conditions as that member is moved through saidweb-forming region, said web-forming region being located at the outflowopening of said flow control unit, said flow control unit includingmeans defining the walls of a generally cylindrical flow control chamberwith the major axis thereof extending transversely to the direction ofmovement of the web-forming member and a forwardly extending, downwardlydirected conduit, said cylindrical chamber being closed except for apair of axially extending, circumferentially spaced openings throughwhich the fluid delivered to said web-forming region is caused to flow,one of said openings forming said inflow opening and the other of saidopenings forming an inlet opening into said conduit, the other end ofsaid conduit forming said outflow opening, a transversely extending,cylindrical rotor disposed within said chamber so as to provide are-entrant passageway within said chamber, within which the uppermostsurface layer of the flowing stream of fluid is continuously circulatedduring operation of said apparatus, the circulatory flow of fluidthrough said chamber intermixing with the main stream of fluid upstreamof said web-forming region to thereby establish a predetermined velocityof the flowing stream in the web-forming region in the direction ofmovement of the forming member in response to the rotation of saidrotor, adjustable drive means for controlling the rotation of saidrotor, said cylindrical rotor being of a diameter such that the spacingbetween the rotor surface and the inner wall of the chamber is less thaninch over a major portion of the surface area of said rotor, the surfaceof said rotor including a plurality of roughness elements, said spacingand roughness elements eflectively controlling the flow instabilitieswhich are normally incident to the rotation of a rotor within acylindrical chamber, the lower wall of said conduit forming an apronplate having a lip on its forward edge which is so positioned relativeto said forming member and breast roll that a portion of the flowingstream of fluid which is delivered to the web-forming region will flowunder stable flow conditions, between said lip and the forming member ina direction opposite to the direction of movement of said forming memberduring operation of said apparatus, the upper wall of said conduitforming a slice member, the upstream edge of said slice member beingspaced approximately /16 inch from the surface of said rotor so as topeel off as large an amount of fluid from adjacent the rotor as possibleand to direct said fluid towards the forming member, and the forwardedge of said slice being positioned adjacent the forming member anddefining the downstream edge of the web forming region, said upstreamedge of said slice member being located between about 2 /2 to 3 inchesbehind the center line of the breast roll and the lip of said apronplate being located from about 1 /2 to 2 inches behind the center lineof the breast roll.

11. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, a breast roll for supporting said member formovement into and through the web-forming region of said apparatus, asource of supply of a fluid suspension of a fibrous material, and a flowcontrol unit having an inflow opening connected to said source of supplyand having an outflow opening through which a confined flowing stream ofsaid fluid is discharged onto said forming member under pressure-formingconditions as that member is moved through said web-forming region, saidweb-forming region being located at the outflow opening of said flowcontrol unit, said flow control unit including means defining the wallsof a generally cylindrical flow control chamber with the major axisthereof extending transversely to the direction of movement of theweb-forming member and a forwardly extending, downwardly directedconduit, said cylindrical chamber being closed except for a pair ofaxially extending, circumferentially spaced openings through which thefluid delivered to said web-forming region is caused to flow, one ofsaid openings forming said inflow opening and the other of said openingsform ing an inlet opening into said conduit, the other end of saidconduit forming said outflow opening, a transversely extending,cylindrical rotor forming a portion of said upper section disposedwithin said chamber so as to provide a re-entrant passageway within saidchamber within which the uppermost surface layer of the flowing streamof fluid is continuously circulated during operation of said apparatus,the circulatory flow of fluid through said chamber intermixing with themain stream of fluid upstream of said web-forming region to therebyestablish a predetermined velocity of the flowing stream in theweb-forming region in the direction of movement of the forming member inresponse to the rotation of said rotor, adjustable drive means forcontrolling the rotation of said rotor, said cylindrical rotor being ofa diameter such that the spacing between the rotor surface and the innerwall of the chamber is less than 3 inch over a major portion of thesurface area of said rotor, the surface of said rotor including aplurality of roughness elements, said roughness elements being between Aand inch in height and the ratio of the spacing between said roughnesselements circumferentially around the rotor surface to the depth of theroughness elements being between 4 and 12, said spacing and roughnesselements effectively controlling the flow instabilities which arenormally incident -to the rotation of a rotor within a cylindricalchamher, the lower wall of said conduit forming an apron plate having alip on its forward edge which is so positioned relative to said formingmember and breast roll that a portion of the flowing stream of fluidwhich is delivered to the web-forming region will flow under stable flowconditions, between said lip and the forming member in a directionopposite to the direction of movement of said forming member duringoperation of said apparatus, the upper wall of said conduit forming aslice member, the upstream edge of said slice member being spacedapproximately inch from the surface of said rotor so as to peel off aslarge an amount of fluid from adjacent the rotor as possible and todirect said fluid towards the forming member, and the forward edge ofsaid lice being positioned adjacent the forming member and defining thedownstream edge of the web-forming region, said upstream edge of saidslice member being located between about 2 /2 to 3 inches behind thecenter line of the breast roll and the lip of said apron plate beinglocated from about 1 /2 to 2 inches behind the center line of the breastroll.

12. In web-forming apparatus of the pressure-forming type, a continuousweb-forming member, a breast roll having an open cellular periphery forsupporting said member for movement into and through the web-formingregion of said apparatus, a drive means connected with said breast rollfor providing a portion of the energy necessary for turning said breastroll, a source of supply of a fluid suspension of a fibrous material,and a flow control unit having an inflow opening connected to saidsource of supply and having an outflow opening through which a confinedflowing stream of said fluid is discharged onto said forming memberunder pressure-forming conditions as that member is moved through saidweb-forming region, said web-forming region being located at the outflowopening of said flow control unit, said flow control unit including anupper and a lower section, portions of which define the walls of agenerally cylindrical flow control chamber with the major axis thereofextending transversely to the direction of movement of the web-formingmember and a forwardly extending, downwardly directed conduit, saidcylindrical chamber being closed except for a pair of axially extending,circumferentially spaced openings through which the fluid delivered tosaid web-forming region is caused to flow, one of said openings formingsaid inflow opening and the other of said openings forming an inletopening into said conduit, the other end of said conduit forming saidoutflow opening, a transversely extending, cylindrical rotor forming aportion of said uppersection disposed within said chamber so as toprovide a reentrant passageway within said chamber within which theuppermost surface layer of the flowing stream of fluid is continuouslycirculated during operation of said apparatus, the circulatory flow offluid through said chamber intermixing with the main stream of fluidupstream of said Web-forming region to thereby establish a predeterminedvelocity of the flowing stream in the web-forming region in thedirection of movement of the forming member in response to the rotationof said rotor, adjustable drive means for controlling the rotation ofsaid rotor, said cylindrical rotor being of a diameter such that thespacing between the rotor surface and the inner wall of the chamber isless than inch over a major portion of v the surface area of said rotor,the surface of said rotor including a plurality of roughness elements,said spacing and roughness elements effectively controlling the flowinstabilities which are normally incident to the rotation of a rotorwithin a cylindrical chamber, the lower wall of said conduit forming anapron plate having a lip on its forward edge which is so positionedrelative to said forming member and breast roll that a portion of theflowing stream of fluid which is delivered to the web-forming regionwill flow under stable flow conditions, between said lip and the formingmember in a direction opposite to the direction of movement of saidforming member during operation of said apparatus, the upper wall ofsaid conduit forming a slice member, the upstream edge of said slicemember being spaced approximately inch from the surface of said rotor soas to peel off as large an amount of fluid from adjacent the rotor aspossible and to direct said fluid towards the forming member, and theforward edge of said slice being positioned adjacent the forming memberand defining the downstream edge of the web-forming region, saidupstream edge of said slice member being located between about 2 /2 to 3inches behind the center line of the breast roll and the lip of saidapron plate being located from about 1 /2 to 2 inches behind the centerline of the breast roll, the upper section of said flow control unitbeing pivotally connected at its lower upstream end within saidapparatus and adjustable means for rotating said upper section aboutsaid pivotal connection, thereby permitting an adjustment of theposition of said slice member relative to said forming member.

13. In web forming apparatus of the pressure forming type, a continuousweb forming member, means for supporting and driving said member, asource of supply of a fluid suspension of fibrous material, a flowcontrol unit defining an inflow opening connected to said source ofsupply and defining an outflow opening through which a stream of saidfluid suspension is discharged on to said forming member under pressureforming conditions as said member is driven, a cylindrical rotor withinsaid flow control unit and having an imperforate outer surface anddisposed within said flow control unit and providing a fluid suspensionpassage along a relatively short are of the rotor and between the rotorand an opposite Wall of the unit and connecting said inflow and outflowopenings, and means for driving said rotor, said rotor being encasedwithin and in substantially uniform close proximity to the walls of acylindrical chamber within said flow control unit except for saidpassage forming arc so as to form a bypass passage around the peripheryof the rotor which is of less cross sectional thickness than said firstnamed passage so that part of the fluid suspension flowing in said firstnamed passage flows between the rotor and the adjacent walls of thecylindrical chamber for changing the velocity of the fluid suspension asit flows through said outflow opening, said flow control unit includinga wedge shaped slice having its tip in close proximity to said rotor andhaving surfaces defining both said bypass passage and also said outflowopening.

14. In web forming apparatus of the pressure forming type, a continuousweb forming member, means for supporting and driving said member, asource of supply of a fluid suspension of fibrous material, a flowcontrol unit defining an inflow opening connected to said source ofsupply and defining an outflow opening through which a stream of saidfluid suspension is discharged on to said forming member under pressureforming conditions as said member is driven, a cylindrical imperforaterotor within said flow control unit and providing a fluid suspensionpassage along a relatively short are of the rotor and between the rotorand an opposite wall of the unit and connecting said inflow and outflowopenings, and means for driving said rotor, said rotor being encasedwithin and in substantially uniformly close proximity to the walls of acylindrical chamber within said flow control unit except for saidpassage forming arc so as to provide a bypass passage around theperiphery of the rotor to receive fluid suspension from and return it tosaid first named passage for changing the velocity of the fluidsuspension as it flows through said outflow opening, said rotor beingserrated on its exterior for increasing the energy supplied by the rotorto said fluid suspension and said outflow opening extending obliquelywith respect to said web forming member so as to project the fluidsuspension flowing through the opening on to the forming member in thedirection of movement of the forming member.

15. In web forming apparatus of the pressure forming type, a continuousweb forming member, means for supporting and driving said member, asource of supply of a fluid suspension of fibrous material, a flowcontrol unit defining an inflow opening connected to said source ofsupply and defining an-voutflow opening through which a stream of saidfluid suspension is discharged on to said forming member under pressureforming conditions as said member is driven, a cylindrical imperforaterotor within said flow control unit and providing a fluid suspensionpassage along a relatively short are of the rotor and between the rotorand an opposite wall of the unit and connecting said inflow and outflowopenings, said rotor being encased within and in substantially uniformclose proximity to the walls of a cylindrical chamber within said flowcontrol unit so as to provide a bypass passage of relatively smallsectional area compared to that of said first named passage andreceiving fluid suspension from and returning it to said first namedpassage, and means for driving said rotor, said flow control unitincluding a Wedge shaped slice having a surface defining one end of saidsecond named passage and defining one wall of said outflow opening sothat the outflow opening extends obliquely with respect to said Webforming member to discharge fluid suspension on said web forming memberin the direction of movement of the web forming member and so that theslice peels oil a layer of stock suspension adjacent said rotor in saidfirst named passage with rotation of the rotor and directs it around therotor in said bypass passage.

16. In web forming apparatus of the pressure forming type, a continuousweb forming member, means for supporting and driving said member, asource of supply of a fluid suspension of fibrous material, a flowcontrol unit defining an inflow opening connected to said source ofsupply and defining an outflow opening through which a stream of saidfluid suspension is discharged on to said forming member under pressureforming conditions as said member is driven, a cylindrical rotor withinsaid flow control unit and providing a fluid suspension passage along arelatively short are of the rotor and between the rotor and an oppositeWall of said unit and connecting said inflow and outflow openings, andmeans for driving said rotor, said rotor being encased within andsubstantially uniformly spaced with respect to the walls of acylindrical chamber within said lfiOW control unit except for saidpassage forming arc for forming a bypass passage connected with saidfirst named passage so that part of the fluid suspension flowing in saidfirst named passage flows through said bypass passage from and back intosaid first named passage to have energy added to the fluid suspension bysaid rotor, said outflow opening being defined by two opposite planewalls so as to extend obliquely with respect to said web forming memberto direct fluid suspension on the web forming member in the direction ofmovement of the web forming member.

References Cited in the file of this patent UNITED STATES PATENTS2,756,648 Lee July 31, 1956 FOREIGN PATENTS 881,631 France Jan. 29, 1943UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,028,298 April 3, 1962 Charles A. Lee

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, line 14, for "plurailty" read plurality column 13, line 7, forFsubstantailly" read substantially line 13, for "its" read it. columnl5, line 40, for "portions" read portion line 16 for "combined" readconfined Signed and sealed thi'saBlst day of July 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

1. IN THE MANUFACTURE OF CONTINUOUS FIBROUS WEBS UNDER PRESSURE-FORMINGCONDITIONS BY THE USE OF A CONFINED FLOWING STREAM OF A FLUID SUSPENSIONOF FIBROUS MATERIAL WHICH IS CAUSED TO FLOW OBLIQUELY INTO CONTACT WITHA MOVING, FLUID-PERMEABLE FORMING MEMBER IN A WEB-FORMING REGION, THEIMPROVEMENT WHICH CONSISTS IN CONTROLLING THE PRESSURE AND VELOCITYDISTRIBUTION WITHIN THE FLOWING STREAM ADJACENT THE FORMING MEMBER BYDIRECTING THE UPPER PORTION OF THE FLOWING STREAM AT A POINT UPSTREAM OFTHE WEBFORMING REGION INTO A VORTEX WHEREIN THE FLUID HAS A GREATERVELOCITY THAN THE AVERAGE VELOCITY OF THE FLUID WITHIN SAID FLOWINGSTREAM, CAUSING A PORTION OF SAID VORTICULARLY MOVING FLUID TOTANGENTIALLY ENGAGE AND PARTIALLY INTERMIX WITH THE UPPER LAYERS OF SAIDFLOWING STREAM, AND MAINTAINING SAID VORTEX BY THE CONTROLLED ADDITIONTHEREOF OF SUBSTANTIAL AMOUNTS OF ENERGY, SAID ENERGY ADDITION BEINGEFFECTED BY A DRIVING MEANS WHICH IS LOCATED AT THE CENTER OF THEVORTEX.